While functions of portable electronic devices have recently been diversified, a device which is advantageous in portability can have a much higher compatibility. For example, even if electronic devices have the same function, an electronic device which is slimmer, lighter, thinner, and simpler can be preferred. Therefore, manufacturers of the electronic devices compete with each other to develop a device slimmer, lighter, thinner, and simpler than other products while having the same or more advanced functions.
As one way of such a trend, the electronic device has external components selectively or necessarily applied therein. Such external components have been gradually becoming smaller, and an interface device capable of recognizing the external components applied to the electronic device also has been becoming smaller.
For example, such external components may be represented as a card-type external component such as a memory card capable of expanding a storage space of the electronic device, a Subscriber Identification Module (SIM) card (so-called a ‘SIM card’) installed to one electronic device in a detachable manner so as to be used by a plurality of users authenticated in different ways, and the like. There is an effort to effectively apply such external components to the electronic device.